The present invention relates to a fiber product comprising cellulosic fiber and polyester fiber and having both a superior flame-proofness and a good touch (hand).
Heretofore, efforts have been made for overcoming the disadvantage common to both synthetic and natural fibers that the fibers are easy to burn. And various proposals have been made for this purpose. With these proposed methods, it is now possible to modify various synthetic fibers, including polyester and nylon, as well as natural fibers to the extent of conforming to domestic and foreign flammability safety standards, using flame-proofing agents specified according to the kind of fibers.
Fiber products containing both natural and synthetic fibers exhibit superior performances as a synergistic effect of the characteristics of both fibers, and because of this advantage they have recently been applied to various uses. Particularly, polyester fiber-cellulosic fiber products, such as woven-, knitted- or nonwoven-fabrics whose main constituent fibers are polyester type fibers and cellulosic fibers, are in wide use as clothing, bed cloth and sheet and interior materials, and a strong demand exists for their flame-proofing. With the conventional flame-proofing techniques, however, it has been impossible to render such fiber products flame-proof to a practical extent in their use as clothing.
It has heretofore been considered very difficult to make flame-proof polyester fiber-cellulosic fiber products. This is closely related to the marked difference in burning mechanism of the two. More particularly, the burning mechanism of cellulosic fibers is carbonization mechanism, while that of polyester fibers is drip mechanism. Consequently, when the fiber product burns, the dropout of flammable substance from the burning system by melting of polyester fiber is prevented due to the presence of carbonized residue of cellulosic fiber, so that the fiber product as a whole becomes easier to burn. This phenomenon, called Scaffolding Effect, is well known. It is therefore evident that even if the polyester fiber and the cellulosic fiber are each independently rendered flame-proof, it is impossible to prevent the above effect. Thus, how to make such fiber product flame-proof has been the most difficult problem.
Attempts have heretofore been made to solve this problem by bonding a large amount of a flame-proofing agent to the fiber product (see Japanese Patent Publication (JPB) Nos. 32000/77 and 31999/78 corresponding to U.S. Pat. Nos. 3,822,327 and 3,907,898). According to such techniques, the flame-proofness may be attained to some extent, but the resulting fabrics are very hard and poor in color fastness, not applicable at all to such uses as clothing and bed cloth and sheet.
Also known is an attempt to achieve the flame-proofing of the fiber product by combining a flame-proofing agent with a triazine derivative coating (see Japanese Patent Laid Open (JPA) No. 126368/83). According to this method, it is possible to attain flame-proofness to a somewhat higher extent corresponding to the presence of such coating, but also in this method a large amount of flame-proofing agent must be bonded to the fiber product to conform to the U.S. DOC FF-3-71 (flame-proofing regulations on children's night clothes) and Article 8-3 (flame-proofing regulations on curtain) of the Shobo-Act (Japanese Fire Proof Act). Consequently, even if a practical level of flame-proofness is attained, a marked deterioration results in point of touch (hand) and color fastness.
As to flame-proofing polyester fiber, Japanese Patent Laid Open Nos. 43221/75 and 43222/75 disclose a method of producing a flame-proof fiber by treating polyester fiber containing a large amount of antimony oxide with a phosphorus compound. It can be seen that the flame-proofing of polyester fiber is attained by this method. However, this method makes only polyester fiber flame-proof and thus is a mere extension of the conventional flame-proofing method for synthetic fibers.
In connection with flame-proofing a fiber product comprising polyester fiber and cellulosic fiber, it is a well-known fact that with a mere application of well-known phosphorus- or halogen-based flame-proofing agents to the fiber product surface, the fiber product does not exhibit flame-proofness. The burning mechanism of such fiber product has been made clear by the analysis of thermal degradation. More particularly, cellulosic fiber begins to undergo a thermal degradation on a lower temperature side than polyester fiber, and a flame-proofing component imparted to the polyester fiber is thereby deprived of in an early stage of thermal degradation of the cellulosic fiber, resulting in that the amount of the flame-proofing component acting on polyester becomes very small and the Scaffold Effect by the cellulosic fiber acts to accelerate the burning of polyester.
Under the above-mentioned facts, it has been a commonly accepted idea of those skilled in the art that even such a flame-proofing agent as is effective for polyester fiber alone does not effective for a blended product thereof with other fibers.